While there are many types of utility carts and similar devices that facilitate the moving of items such as groceries and laundry, such devices do not provide for ease of operation over varied terrain, inclines or uneven surfaces, for example, up and down stairs, over ramps with slats or over curbs.
Some of the disadvantages of the existing devices generally include the relatively small wheel sizes which present difficulty when an operator attempts to move a device over protruding surfaces, and also the absence of an integral braking system which will prevent the device from rolling away while the device is being move An explanation for the corresponding difficulty in operating a device with smaller wheels is that a smaller wheel will contact the rising surface or the outermost edge of a protruding surface, for example a riser of a stair, before it contacts the more horizontal portion of the surface. Thus, the device must be moved over the outermost edge of the surface, which is normally on a substantially different angle than the line of force being directed on the cart by a user. This change in angle presents increasing difficulty for the user to maneuver the device.
Generally, large wheel systems have been avoided due to the tendency, for example, of a large wheel device to roll downward under its own weight when a user moves the device upstairs or over inclines and pauses before reaching the top. The existing devices do not provide braking systems to overcome the disadvantages of large wheel systems.